Rest compartments in an aircraft are already well known; in long-haul flights of relatively long flight duration they are used as rest areas by members of the on-board crew. Rest compartments can be positioned at various places within the aircraft, which depends, in particular, on the respective aircraft type or on its size. For example, rest compartments are known that are situated above a passenger cabin and that extend from a region of the cabin ceiling to the top of the aircraft fuselage, as is, for example, shown in EP 0901964. In such overhead rest compartments the arrangement of a narrow and low passage is advantageous so that the crew members who are within the rest compartment can, for example, move from an entrance region to a sleeping region. This passage is arranged between two walls that extend from a floor of the rest compartment downwards in the direction of the cabin. This passage is, for example, arranged in such a manner that a free walking height of up to 1.5 m can be achieved. For this reason the walls at the bottom of the rest compartment, which walls delimit the passage, are relatively pronounced, and consequently the space situated underneath it can hardly be used for installations other than passenger seats or partition walls.
Larger monuments, for example aircraft toilets, which are arranged in centre regions of the cabin and which are designed in the conventional, essentially cuboid, manner, cannot be integrated underneath such a rest compartment because their design heights are such that the passage of the rest compartment would project into toilet compartments situated below it. As a result of this the toilet compartments could only be used with the user stooping therein, which would, however, severely limit passenger comfort within the aircraft cabin.